Integrated circuits are formed through a process known as semiconductor device fabrication. The semiconductor device may be formed on a thin slice, or wafer, of semiconductor material, such as silicon crystal. The wafer serves as a substrate for microelectronic devices built on the wafer. During fabrication of these integrated circuits, the silicon wafer is put through a sequence of wet chemical processing steps. One wet chemical processing step in the sequence is electrochemical deposition, commonly known as electroplating.
In the electroplating process, electrical current is used to deposit metal ions from a solution onto a wafer, forming a film or patterned structure of metal on the wafer. Certain semiconductor packaging technologies, such as Wafer Level Chip Scale Packaging and Flip Chip, involve multiple electroplating steps. Many electroplating processes make use of semiconductor fabrication plant (fab) equipment. The fab equipment is designed to plate a single wafer at a time causing the electroplating process to be slow. The fab equipment is also typically very expensive. In addition, downtime is common due to high maintenance requirements and plating chemistries are expensive due to the small quantities used. These factors result in a high cost per wafer to perform electroplating.
Plating equipment used in other industries, including batch and continuous processing systems used in traditional semiconductor packaging are considerably less expensive and more efficient than the fab equipment. This plating equipment may include that used for printed circuit boards or leadframe plating lines. Such plating equipment provides typical throughputs which are approximately ten times greater than that of fab equipment at a cost that is typically half that of the fab equipment. Currently, however, there is no way to electroplate semiconductor wafers using printed circuit board or leadframe style plating equipment.